A synopsis of Veratrum, including commentary on species and character evolution within the genus, is presented. The circumscription and relationships of infrageneric taxa are evaluated using parsimony analyses of ITS (nuclear ribosomal) DNA sequence data of 26 representative taxa. Proposed new infrageneric circumscriptions, strongly supported by tree statistics and topologies, are correlated with potential morphological synapomorphies at the proper level of universality. Based on our analyses, Veratrum is circumscribed broadly (including Melanthium) and divided into two sections and two subsections (most with novel circumscription). This modified infrageneric classification involves reassignment of Veratrum subgenus Pseudoanticlea as subsection Pseudoanticlea. Although interspecific relationships are not highly resolved, the molecular data provide strong support for placing several species previously of unknown affinities and also validate several generalizations concerning character evolution within Veratrum.